WASHINGTON (AP) _ The assembly line job paid well, and Ella Williams appreciated the money. Williams claims it only took a few months, however, before her hands curled into claws, her wrists swelled and her shoulders ached from the repetitious work of building Toyota engines.

She asked for a different job at Toyota's Georgetown, Ky., plant, a request that set her on a path to the Supreme Court and a potential ruling on whether employers must make special accommodations for workers with injuries such as carpal tunnel syndrome.

The court hears arguments in Williams' case Wednesday.

Both business and civil rights lawyers say the court's ruling could fill in a question lingering from the landmark Americans With Disabilities Act: Is a worker disabled _ and thus entitled under the law to some accommodation _ if he or she can do some but not all of a particular job?

``I think it's an important question for business generally _ what the definition of disability is under the ADA,'' said John Roberts, Toyota's lawyer before the high court. ``Companies are looking for a little clarification.''

Williams' lawyers and a long list of civil rights and labor groups claim that Toyota really wants a narrow definition of disability that runs counter to the ADA's intent. Williams wants to work, and the 1990 law was supposed to make it easier for people like her to get and keep jobs, her backers argue.

``The facts of this case perfectly illustrate the way that employers like Toyota are pushing for an interpretation of the ADA that creates the ultimate Catch-22 for people like Ella,'' said Catherine Hanssens, director of the AIDS project of Lambda Legal Defense and Education Fund.

``If Toyota prevails in this case, the only way many people will be able to prove they're covered under the ADA is to prove that they ... are too disabled to hold the job. It makes absolutely no sense, and it was not what the ADA was intended to do.''

Toyota does not argue that Williams has an ``impairment,'' but claims it should not have to custom tailor a job for her. The two sides disagree over whether Williams resigned or was fired after she refused to perform tasks that her doctor said would aggravate her symptoms.

The ADA is perhaps best known for requiring wheelchair ramps in buildings across the country. It bans job discrimination against the disabled, requiring employers to offer reasonable accommodations to disabled people who are otherwise qualified to perform jobs.

The law defines disability as ``a physical or mental impairment that substantially limits one or more of the major life activities,'' such as working or caring for oneself.

Williams and her husband moved across Kentucky in 1990 to take jobs at the Georgetown Toyota plant, where workers could earn more than $60,000 a year. A high school dropout with three children and four stepchildren, Williams was eager for the high wages and good benefits, her lawyer has said.

Williams started work in 1990, and quickly developed repetitive stress injuries in her wrists, neck and arms.

She sued under the ADA, and also filed a worker's compensation claim. Both were settled, and in 1993 Williams returned to Toyota with a doctor's instructions to perform only light duty.

She was assigned a job inspecting paint, which she could do without pain. In 1996, however, Toyota told Williams that all quality inspectors must be able to do four different inspection jobs. Williams said one of the new tasks caused pain and numbness in her arms, hands, shoulders and neck.

She asked to return to her previous assignment, but Toyota refused. Williams sued again under the ADA, saying Toyota did not make proper accommodation for her disability.

A federal appeals court ruled last year that Williams is disabled under the ADA because even though she can perform some manual tasks, she cannot do much assembly line work.